220 
Letters, Extracts, and Notes. 
six occasions, and, what is more surprising, in the British 
Islands and in Heligoland. 
I am, Sirs, yours &c. 
20 Via Pandolfma, Cecilia Picchi. 
Florence, Italy. 
November 17 th, 1909. 
Heel-pads on Young Birds .—It lias been pointed out to 
us that the existence of heel-pads in certain species of birds 
that nest in hollow trees (see Gunther, Ibis, 1890, p. 411, 
and Stonham, Ibis, 1909, p. 619) was well known to Nitzsch, 
who described and figured this curious structure in his 
‘ Pterylographie, 5 p. 134. Taf. v. Nitzsch says (Engl, 
transl. p. 91) : — 
“In Micropogon erythropygos (i. e , Trachyphonus mar- 
garitatus) I found on the lieel-joint a peculiar circlet of 
acute tubercles, such as I have also detected in young 
Wrynecks.” 
These heel-pads have therefore now been detected in six 
species of two families, namely :— 
PlCIDJE. 
lynx torquilla. 
Gecinus viridis. 
Dendrocopus macei. 
Brachypternus aurantius. 
Capitonidas. 
Cyanops asiatica. 
Trachyphonus mar garitatus. 
There can be little doubt, we think, that the use of this 
peculiar structure is to enable the young birds to ascend the 
smooth interior of the holes in the trees in which they are 
hatched. But it would be very desirable that the young of 
other birds that breed in hollow trees should be examined 
to ascertain whether they carry heel-pads or any similar 
organs, and we hope that some of our many correspondents 
in various parts of the world will turn their attention to this 
subject and let us know the result.— Edd. 
The Lake-Ngarni Expedition. — Letters received from 
Mr. Woosnam, dated October 1st, 1909, announce that the 
party was still on the banks of Lake Ngami, and was doing 
